The objective is to study the life histories from age 10 to 22 of an epidemiologically defined population of approximately 300 mentally subnormal and borderline young people identified and studied in 1962. We are examining their socialization, education and post-school careers, and how these were influenced by their subtype of mental subnormality, their social relationships and activities, and by the kinds and qualities of community services they and their families received. A second population who are not mentally subnormal but who are matched with the mentally subnormal on age, sex, occupation of father and type of housing are being used as comparisons to determine the extent to which young people with different subtypes of mental subnormality may have undergone developmental and socialization processes different from the comparison population. Life histories are being obtained through interviews with the study subjects and their parents. A variety of existing research and administrative records are being used to cross-check, supplement and complement the interview and observational data.